Voltolization apparatus and method



Feb. 27, 1940.. J, E, CLEMENS' ET AL 2,191,787

VOLTOLIZATION APPARATUS AND METHOD Filed Dec 17, 1936 2 Sheets-Sheet 1 7207A T/IV6 f REA c 7/0 .D/sc

CHA MB ER.

62 ID I J8 M092 7' MED/UM IIVAE T f0 PUMP 4 VESSEL a For-A v-wva 345a 725A c7-'/oN CHAMBER Feh 27, 1940- J. E. CLEM-ENS ET AL I 2,191,787

VOLTOLIZATION APPARATUS AND METHOD Filed Dec. 17, 1936 2 Sheets-Sheet 2 MEDIUM /RAC7'/ON,

CHAMBER Patented Feb. 27, 31940 STATS Matheson, Union, N.

.l'., assignors to Standard Oil Development Company, a corporation of Delaware Application December 17, 1936, Serial No. 116,256

9 Claims.

l The term voltolization has been applied in' recent years to the treatment of materials with silent electric discharges under vacuum. The process has been employed commercially for the thickening of mineral and fatty oils. In general the usual voltolization processes employ an alternating current of about 60-10,000 cycles a vacuum of 0.5 to 0.9 atmosphere and a voltage of 5,000-25,000 volts. The apparatus usually consists of a condenser type arrangement with the discharge taking place between two insulated electrodes, in which space is circulated a film of oil or other material to be treated. The latter is commercially achieved by the use of a rotating plate partially dipped in the charge stock, the upper part of the plate carrying the film subjected to the discharge.

One object of this invention is to obtain a higher degree of voltolization in a more eflicient manner by the use of low voltage direct current.

Another object is to carry out a discharge between uninsulated electrodes, one of which is in the form of a grid. Another object is to avoid the local overheating or deterioration of the feed stock (usually encountered due to hot spots when it is fed between electrodes) by placing the charge not between the electrodes but behind the cathode grid and allowing the discharge particles traveling through the grid electrode to impinge upon the feed stock. Further objects will be apparent from the subsequent disclosure.

The invention will be more clearly understood from the accompanying drawings in which Fig. 1 is a diagrammatic cross sectional elevation of a complete assembly-of a \voltolization apparatus operating on direct current. Fig. 2 illustrates a modified form of electrode assembly, while Fig. 3 is an electrode assembly suitable for. operation with alternating current. Fig. 4 shows a front view of the grid and plate assembly.

Similar numerals refer to similar parts throughout the several views.

Numeral I designates a reaction shell orchamber capable of withstanding high vacuum. It'is maintained by a suction pumpevacuating at 2. In this chamber is located vessel 3 filled with oil 4 or oily organic compound on other raw material'to be submitted to the electric discharge. Partially immersed in this oil isa totating disc or plate 5, practically half the surface of which is in the oil bath. This plate is rotated by shaft 6 extending out of vessel I through packing gland 'l, to driving gear 8 driven by motor 9. This shaft and reaction chamber are grounded at II].

By rotating plate 5, an oil. film I I is formed on the surface subject to the action of the positive ions of the discharge, thereby causing a gradual thickening of the oil mass 4.

The discharge is produced as follows:

A positive electrode I2 which may be of any shape, such as wire, rod, tube, bar, grid, etc., is led into chamber I through insulator I3. Opposite this. electrode and as close to plate as possible (without actual contact or Wetting) is placed the negative electrode I4 which is in the form of a grid or foraminous plate having a large amount of open space thereby allowing the positive ions l 5 to pass therethrough and impinge upon the oil film II carried by plate 5. Grid electrode I4 is connected by means of conduit IE to .shaft 6 by sliding contact I'I. It may be suspended more rigidly from the top of chamber I by supports such as I8. With the connections shown, substantially no electrical potential gradient across the narrow space between grid electrode I4 and disc 5, the electrical potential in disc 5'and electrode I4 tending to be equalized by their connection in common with'conducting shaft 6.

A cooling coil I9 may be inserted in the oil reservoirs 3 so as to prevent overheating since the ion impact on the grid I4 and oil film II raises the temperatures thereof;

Provision may also be made for bleeding in at valve 20 small amounts of various gases or vapors such as helium, argon, air, nitrogen, formaldehyde, hydrogen sulfide, sulfur dioxide, ammonia, etc. I

It will be noted that in Fig. 1 only one side (ll) of the rotating plate'is subjected to the discharge. Fig. 2 illustrates a modification whereby two grid electrodes and two positive electrodes may be arranged so as to voltolize the 011 film on both sides of the rotating plate 5, the discharge zones being designated by'I5. A multiple plate apparatus employing these principles is likewise possible.

The apparatus in Figs. 1 and .2 is designed for direct current operation. Although alternating current can be employed, only one-half of it will be utilized for thickening the oil, as can be seen from the circuit. However, it is possible to obtain a highernefliciency with alternating current by employing the assembly shown in Fig. 3. The two plates 5 are insulated from each other by insulating member 2|. An alternating current dis- II IHI charge takes place between grids I 4 intermittently from one grid to another as the polarity changes, and the positive ions passing through the grid impinge on the oil surface I I carried by rotating discs 5. The latter are connected with the electrodes by sliding contacts 22; hence the same electrical potential is impresed on each disc 5 at each instant as on its adjacent grid electrode I4, with which it is connected in parallel to an A. C. power source, e. g., through a lead or bus bar 23. It will be noted that since only one phase voltolizes at a given instant, this method resembles the direct current procedure to that extent.

A front view of the grid and plate assembly is shown in Fig. 4. It will be seen that, since about one-half of the surface of the rotating plate 5 is immersed in oil bath 4 in reservoir 3, the grid I4 need be only semicircular in shape facing the exposed oil film on plate 5.

The distance between the anode I2 and grid I4 may be any convenient distance, although it is preferable to maintain it at to 2 inches. It is also preferable to construct grid I4 from Monel metal, platinum, chrome steel (18% Cr and 8% Ni), nickel-chromium steels, etc., although Monel metal has been found highly satisfactory for this purpose.

Grid I 4 should be placed as near oil film II as is practicable without wetting the grid, since the oil will carbonize on the surface, cutting off ion permeability. Of course, the ion impact on the grid tends to clean the grid surface to a great extent. As pointed out above, in order to obtain the greatest amount of ion bombardment on the oil film I I, it is desirable to employ a grid having a maximum ratio of open space to metal area. It is also preferable to maintain as fiat a grid surface as possible so as to obtain a more f'even discharge from the anode.

Rotating plate 5 is preferably constructed of a conducting material such as aluminum, bronze, Monel metal, chrome steel, manganese-silicon bronze, etc. Since acids and other corrosive compounds may be present, it is essential that a I corrosion resistant material be employed so as to avoid contamination of the product. This plate has been observed to rise in temperature to about 150 F. after several days operation. Where such elevated temperatures are not desired, cooling may be resorted to, although suflicent cooling is effected by radiation, provided the current density is kept at about '10 to 30 milliamperes per square inch of plate surface.

By employing the apparatus disclosed in this invention it is possible to 'obtain excellent results with potentials of only about 300-600 volts. This, of course, depends to a great extent upon the apparatus, the pressure, and the inert gas present. For instance, if hydrogen is present in chamber I, a lower potential will be necessary to obtain the desired thickening action than if nitrogen were present.

In this type of apparatus, it is essential that a low pressure be attained. It must be substantially below 10 mm. of mercury, say 5-mm. or 1 to 2 mm. or even a fraction thereof. In this respect the process differs considerably from other methods of voltolization which are preferably carried out at 20 mm. or higher pressure.

Many advantages are gained by the type of voltolization described. herein. Due to the relatively low voltage employed, dielectric failures or difiiculties are avoided. Since the type of discharge is not affected to any appreciable extent by the conductivity of the material treated, it is possible to voltolize highly polar compounds such as acids, bases, phenolic compounds and salts, which have been heretofore impossible 'to thicken in the usual condenser type discharge wherein the charge stock is passed between the electrodes. Furthermore, it is even possible to voltolize solid or semi-solid materials by this means. This type of treatment is not limited to liquids or solids, but is likewise adapted for gaseous raw materials.

The temperature of voltolization is preferably kept at 50-150 F. although it is possible to carry out the treatment at temperatures as low as -l00 F. or as high as 450 F.

The following examples illustrate the many phases involved in this invention:

Example 1 Example 2 A mildly refined Pennsylvania 011 of 150 viscosity at 210 F. was voltolized at 425 volts and 3 mm. Hg pressure with a current density of 15 milliamps per sq. in. in an apparatus similar to that shown in Fig. 1. At the end of 20 hours, the oil had a viscosity of 688 at 210 F. and proved to be an excellent lubricant as well as a blending agent for dispersing sludge in lubricating oils. The current consumption was kwh. per gal.

Example 3 Some stearophenone was voltolized as in.EX ample 2 for 30 hours, and a. thick product was obtained which in 2% concentration lowered the pour point of the Pennsylvania oil by 20 F. The

current consumption was 30 kwh. per gal.

Example 4 Rapeseed oil containing 8% sulfur was voltolized as in Example 2 for 7 hours, producing a thick oil which when blended in 10% concentration in an SAE 20 mineral lubricating oil, was able to carry all of the weights on the Almen machine without any bearing failure. The Almen test dealing with extreme pressure lubrication is described in U. S. Patent 2,001,861.

This invention is not limited to any theory of operation or any specific examples, but only to the following claims in which the intention is to cover the invention as broadly as the prior art permits.

of positive ions penetrating through said space until a desired substantial thickening of the organic compound is obtained.

2. Process of voltolizing liquid oily organic compounds which comprises setting up an electrical potential difference between opposite ends of a gas ionizing zone under conditions to produce positive gas ions projected toward a surface of the liquid organic compound being treated,

type negative electrode spaced from said positive electrode, electrical connections from said electrodes to complete an electrical circuit including electrical potential difference between the positive electrode and the grid-type electrode to produce positive ions projected through openings in said grid-type electrode, and means electrically connected to have the electrical potential of the grid-type electrode for exposing a liquid surface of the organic compounds to be thickened to bombardment by positive ions projected through openings in said grid-type electrode.

4. Apparatus for voltolizing an organic material comprising a plate adapted for rotation,

means adapted to maintain on a surface of said plate a liquid film of the organic material having a gas-liquid interface, a grid-type cathode disposed parallel to said plate surface at a distance to be just out of contact with a liquid film on said plate surface, a positive electrode situated about to 2 inchesfrom said grid-type cathode with the grid-type cathode interposed between said positive electrode and said plate; electrical connections from said positive electrode to a source of electric current, electrical connections from said grid-type cathode in an electric circuit for setting up an electrical potential difference between the grid-type cathode and the positive electrode so as to project positive ions emanating between said grid-type cathode and said positive electrode through openings in said grid-type cathode into contact with the-liquid film at said gas-liquid interface, and electrical connections between said gridtype cathode and said plate for impressing substantially the same electrical potential on both said grid-type cathode andsaidplate.

5. Apparatus for thickening an organic material comprising a pair of parallel plates electrically insulated from each other and adapted for rotation, means adapted to maintain liquid films of the organic material on surfaces of said plates, a pair of parallel grid-type electrodes spaced apart between said pair of plates, each of said grid-type electrodes being disposed adjacent to one of said plate surfaces to be just be yond contact with a liquid fllm on its adjacent plate surface, means for connecting said gridtype electrodes to a source of alternating current for setting up electrical potential differencesbetween said pair of grid-type electrodes so as to project positive ions emanating between said grid-type electrodes alternately through openings in each of said grid-type electrodes to liquid films on their adjacent plate surfaces, and electrical connections from the source of alternating current to said plates for impressing the same voltage at each instant on each of said platesas is impressed on its adjacent grid-type electrode;

6. Process in accordance with claim 2 in which the potential difierence between the opposite ends of said gas ionizing zone is from 300 to 600 volts. 7. Process in accordance with claim 2 in which the electric potential diiference between the opposite ends of said gas ionizing zone is set up at a pressure below 10 millimeters of mercury.

8. Process in accordance with claim 2 in which the electric potential difierence between the opposite ends of said gas ionizing zone is sufficient to maintain a current density of from 10 to 30 milliamperes per square inch.

9. Apparatus in accordance with claim 3 in which said means for exposing a surface of a liquid organic compounds to the action of positive ions is a 'plate adapted for rotation, the lower section of which is immersed in a reservoir containing said organic liquid compounds.

JOHN E. CLEMENS. GEORGE L. MATHESON. 

